Telephony.



x a l i llr INVENTQK .ELMER R CQRWIN,

. "1/ af /fd if WATT() ,RXE Y E. R. CORWHL YELEPHONY.

APPLzcmmN msn JULY so. 1J.

E. Hv CQRWM.

TEiPwNY.

Meow mu) mw 1915.

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Patented Muy 30, 1916.

INVENTOR QELMRR CORWN 3% TELEPHONY.

mmm/mow man uw 30,1915.

Pnhfnm'l May 30, 1916.

4 SHELTSY-SHEET 4.

ELMER. R. CORW F*I 4 INVENTRT L UNITED STATES PATENT OFFICE,

ELMER B. COR'WIN, OF CHICAGO, ILLINOIS, ASSIGNOR TO FRANK B. COOK CCLLWIPANY,` 0F CHICAGO, ILLINOIS, .A CORPORATION OF ILLINOIS.

TELEPHONY.

Application filed July 30, 1915.

To all whom it may concern Be it known that I, Emma R. CoRwix5 citizen of the United States.y residing at Chicago, in the county of Cook and State of Illinois` have invent-ed a eertain new and useful Improvement in Telephony. ot' which the following is a full.y clear, concise, and exact description, reference being had to the accompanying drawings, forming a part ot this specification,

My invention relates to telephone exchange Systems and,` in one of its aspects` embraces a telephone exchange system whose telephone. lines are di\ ided into groups, ex change operators equipment at a plurality ot ope tutors positions, and a calling line operated distrihuter Switch for each group of .lines and common to the lines of such group t'or associating the equipment of any ot the operators` available, with the calling line emi'iloying it. Theee groups ot' lines are preferably divided into minor groups. the linee of eaeh minor grouli having line switches which are preferably less in niunher than the lines of sueh ininor group. Each group of line switches is desirably provided with master Switch in interchangeable relation therewith tor determining the switeh that is to he used. ()t.her lwitehes are preterahly added for extending Calling lines beyoud the aforesaid line switehes. these additional line extending switehes being preterahly less in number than the first switcherl and being desirahly divided into as iuauy groups as 'there are major groups otl lines. the. added line extending \\vit(^hes ot' eaeh group ot' Such switeheel pertaining to a iuajor group of telephone lines; having asoeiated therewith taeility for estahlishing their aseov eiation with an operator. the inviti-hesl ot' one group being adapted tor assoeiation with one operator. the Switehes ol" another group being adapted for assoeiation with another operator. ete.

AS the invention is preferably praetised there iS provided a plurality ol holding switches tor eaeh operator (eat'h holding switch relating to a i'litl'ereut, major group ot' telephone lines) and a rail di tributer switch for eaeh major `group oty telephone lines whereby any holding witeh mai be aenoeiated with any railing line in an)` group so that all (falling line may have asa-ess to any operator4 The various line mi itt-hea and line extending switrhes are deuirabli oper- Specication of Letters Patent.

Patented May 30. 191 (i.

Serial No. 42,707.

ated by calling subscribers through 'the interinediation of the holding switches and eaeh operators telephoneis preferably lirought: into interchangeable aeoeiation with hei' holding Switehes by means ot automatically operating switching ineehaniin. The firstswitehes that operate to extend Calling linee are desirahly provided with wipere whose waiting eontaeteA eonstitute terminale perl taining to railing linee; while the additional line extending vita-hes are'v desiraiiy provided with wipere whose waiting contacts are eonneeted with the wipere` 'tor the tirent witehee that vulling lines are init-iallf.' extended by serially related ewitehes oper@ ating toward the calling linee rather than away therefrom, The eall distributor switches preterahly also operate as master switehes in their relation to the added line extending Switehes and also in their relation to the holding switeheq and the operatore are desirahly brought into telephonie con neetion with ealling lines by way ot the line extending switehee and the holding` 'uwitehee that are brought into telephonie oonneetion with operators through the aid of the Call distributer Switehes.

The master switches of the System of my invention are desirably provided with eirenit interrupterel individual thereto and whieh eireuit interrupters are brought into interehangtaible aeoeiation with the line extending ewitehee hy the inaster Qwitehee to elli-et the operation ot the line extending Switehe. eaeh line extending it'en thus be ing temporarily :issvfiated with :i viren-it inA terrupter that'. when funt'ztioning. limited to but one line extending su iteli to eliminate the posuibility ot faulty operation aid doubling up of eonneeiions.

The eyatein ot' the invention aleo ileeiraliljv includes means whereby the operattusi tele phones4 that are to be :lssoriated with railing linee are pre\ ented troni having rfaut-h aseoeiation. by the equipment of calling lineet during the time that suvitelieeI are Qeelting to establish eonneetion between railing liners and the operators whereby the opi-raton:y are relieved ot" the noise whirl: is attendant upon the ealling line extending operation.

The l vste1n ot the invention-also deedrably inrludes a master Switeh for iuterrhengecilile aeiweiation with link eonneetors that are provided with Signal devieeav individual thereto. these signal devicesv and their eir SUS cuits` fsirr., associated with idle link connectoi enabling the master switches to stop ipinving drawings f ,when collectively, diaa min ,onlinethepreterredembodt nient ol" the invention', and Figs. 3 and 4. taken coilcci-ively, illustrate one form of the invention a.

Lilie parts are acters of recrecw flor-ix, iigures.

i have chosen aktiioufar-i line exchange to demonstrate the manner in which. the inwiltion may be '[iiai-tiseil, Figs. i and 2 generally illustratingrr such :in exchange. The lines are subdivided i major groups, there being live liuiidr-el in in cicli major group in the example chosen. Each major group is subdivided into ninna groups .of preferably a hundred lines each. ln Fig. 1 ot' the drawing two lines ot earn hundred line niinor group are illustrated, The lines the ir-t niiiior group oi' il. i i major group may be numbered l to li second ininor group` 101 to lill. ctc., as indi- ^;'.-'s'i! in ["ig. l. 'The lines in the lirst minor group ot the second major group ine-,y ne numbered 501 to t300;l the second minor group, ($01 to 700, etc.

The substation equipment may be of an)T suitable common battery type, each substa tion having a telephone switch hook 1, a telephone receiver a telephone transmit` ter 3, a call bell 4, and a condenser Each line has a line relaiv 3, the line relays of the lines of each minor group having switch contacts that are in common cor ation with a linz. -itrh (,lriving relay T wi :h is thus common to the lines ot the mini up to whirl'. :i pertains This relay in control" relation to a. master line switch 3 t 'it individual to the relay T, there thus being one master line switch 8 for cach minor group of lines and which master line switch is common to the lines of its minor group. The wipers ot the switch 8 are provided with sets of 'uiting contacts.` prcferably ten, though but tive sets ari` shown in Fig. l.. Each et ol.' waiting conti'. 'i is Til the i'iiterent .Killa reist line switch to which such contacts are in,

dividual in condition for operation. In thc embodiment of the invention illustrated the operation of such line switch that is thus placed in condition for operation is eected by a calling subscriber in the minoi group having such line switch, the operation of this switch continuing until the Wipers thereof engage the waiting contacts pertaining to the calling line, it being understood that the wipers of each line switch 9 are provided with as many sets of waiting contacts as there are lines in the minor group to which such line switch belongs Wliereby each line switch may have access to each of the lines in the minor group of lines having such line switch. l do not wish to be limited, however, to the places at which the line switches have their operation initiated and controlled.

The wipers of' each line switch 9, in addition to having a set of waiting contacts in the associate switch 8, also have a set of waiting contacts in each of thirty line eX- tending switches 10 assigned to the major group having such line switch 9, the similarly positioned waiting contacts in' the thirty switches l0 being in multiple connection. For lackof space the diagram, Fig. l, illustrates but twelve line extending switches 10 per major group of five hundred lines. In the example chosen, each line extending switch 10 has fifty Sets of waiting contacts, there being titty lin` switches 9 in the major group having the thirty line extending switches l0. The thirty line extending switches 10 pertaining to each major group are apportioned, in equal number, among two operators A, B each of whom may handie traflic ot' both major groups. Figs. 1 and 2 show six switches 10 (instead of the complete quota of fifteen) of each group ot thirty in association with each operators position. The set of wipers in each switch 1() is represented by a set of waiting contacts in a will holding switch 11. There may be two such switches 11 pertaining to each operators position A` B, one of these switches l1 at an operators position having waiting .'oiitacts pertaining to one subgroup of fifteen line extending switches 10 relating to one niajor group of five hundred lilies and the other ot' these yswitches 11 having waiting contar-ts pertaining to one subgroup ot' fifteen line extending switches 10 relating to theI other major group of five hundred lines. By thisarmingement each operato' has access to all ort' the lilies in both iizziyitwril i; to one group of linxl cxtending Agitilowil? liclongllig to Qatli miljOI group ai neiephonc lines, this relationship being effected through the intermediation of the holding switches 11 to which the switches 12- also occupy the relationship of master switches) the wipers of each switch 12 hav ing as many `sets of waiting contacts as there are operators positions, two in the 'example chosen. By this switch 12 a calling line in either major group may be associated with either operator. The upper set of waitmgl; contacts of the upper switch 12 is indivitual to the upper switch 11 of operator A and the lower set of waiting contacts of the upper switch 12 is individual tothe upper switch 11 of operator B. The upper set of waiting contacts of the lower switch 12 is individual to the lower switch 1-1 of operator A. and the lower set of waiting contacts of the lower switch 12 is individual to the lower switch 11 of operator B.

As the invention'is preferably practised, the wipers of the call distributer switches 12 normally rest upon a set of waitingr con-- tacts. When a call distributer switch 12 is associated with a calling line in the major group having such switch 12 (an association which is effected by the relay 7 employed by the calling line), said switch 12 associates a holding switch 11 of one operator with such calling line. The line extending switch driving relay 13 individual to such employed switch 12 elfects the operation of rclay equipment (diagrammatically indicated at 11- in Fig. 2) individual to the call l1olding switch 11 of one operator that has become associated with the calling line in the major group having such employed switch 12. Mechanism of such relay equipment 14 causes the other switch 12 to associate a holding switch 11 of the other operator with lines of the other major group. by which ar rangement lines of either major group are not deprived of access to an operator. The operators are provided with holding relay selector switches 15 for coupling employed holding switches 11 with their telephone equipments. The wipers of the switches 11 `are normally' resting,r in connection with soV some set of waiting contacts individual to some switch 10. The relay 13 pertaining to the employed switch 12 operates through the call holding switch 111that is now coupled with the employed switch 12 to set the switch 10 (individual to the set yol waiting the calling line until the switch 15 is moved to couple the employed "switch 11 with the operator having it.- The two call holdlng switches 1l provided for each operator are associated with thirty link connector switches 16 provided for the same operator (there being but ten of such switches 16 shown for each operator for the sake of simplicity). Each switch 16 may becomeconnected with either of its two associated switches 11 as each switch 16 is provided with as many sets of waiting contacts as there are sets of waiting contacts in both the switches 11. There are thirty sets of wa1tving contacts for each switch 16 in thehexample chosen. Each group of thirty switches 16 is provided with a master switch 17 having as many sets of waiting contacts as there are switches 16 (thirty in the eX- ample chosen). each set of waiting contacts being individual to a switch 16. The wipers of this master switch 17 normally rest in association with some unemployed link connector which may have a suitable means for connection with called lines yor other calling line extensions, one of these link connectors being illustrated with a con necting plug 18 adapted for reception within jacks 19 in extending calls. Each link connector may be provided with a lamp 2() to designate it or determine it t'or use. The master switch 17 will cause the signal 20 of the link connected with themaster switch to glow so that the attendant operator will use only the plug or other connecting device 19 to which thc glowing` lamp 2() is individual. When the switch 15 has become associated with the employed holding switch 11 and when the calling line has been extended by the operation of the-employed switch 10, the operators telephone set is connected with the calling line and, if desired.r the call lamp 21 may simultaneously be associated with the calling line to attract the attention of the operator if she is not at her position. Having ascertained the number of the line that is to `be called, the operator will insert the plug-18 individual to the glowing lamp 20 in the jack 19 ol thc wanted line, whereafter the operator will manipulate the manual switch 22 to operate the switch 16. individual to the employed plugr 1S and whose wipers are connected with such plug. to bring the wipers of this switch 16 into engagement with the waiting contacts that are connected with the employed waiting contacts of the employed switch 11 and the wipers of the employed switch l0. An established connection bctween callingr and called lines thus includes waiting: contacts pertaining: to the calling.r

line, the wipers of an employed switch 9 engaging these waitingr contacts. thc waiting contacts of the employed switch 10 that are connected with the wipers of the employed switch 9, the wipers of the employed switch 1l), the waiting contacts of the employed switch 16 that are connected with the wipers of the employed switch 10, the wipers of the employed switch 1G, the con necting plug 18 individual to the wipers of the employed switch 1G and connected therewith, and the jack 19 ot' the called line receiving the plug 18. lVhen the employed switch 16 has moved its wipers into connection with the calling line. the wipers olI switches 11 and 17 are iunved into connection with the next idle waiting contacts.

The apparatus which is employed in performing the operations generally described in connection with Figs. l and 2 is illustrated in diagrammatic detail in Figs. 3 and 4 wherein l have illustrated two telephone lines included in thc same minor group. ll'hen a falling subscriber initiatesI a call he removes his receiver L preparatory to securing connection with some idle operator to extend the calling line .into connection with thc called lineV or some other calling line extension. The switch hook trom which the receiver has been removed establishes a circuit traceable from thc common grounded battery 23 (whose. illustration is repeated for the sake of simplicity), through the resistance coil 24. say of one hundred ohms resistance. the upper armature switch of the cutoff relay 25 and its Contact. both sides of the telephone line by way of the switch hook, receiver and transmitter at the calling station and the alternate contact of the switch hook. the lower armature, switch of the cutoff relay Q5, the windingr of the line relay G, to ground. The lower armature switches of the line relay 6 are grounded and the contacts of these armature switches that pertain to the lines of a lninor group that includes the calling lhue are connected with the contact of the armature switch of relay 2G that is common to the lines of such minor group. there being one such relay 2li for the lines of cach minor group. lien the line relay (3 of the callin;V line is rmigiacd. a circuit is established traceable l .n its lower and grounded armature switch. through the contact of such switch. the armature switch and contact ot said relay QG. the line switch driving relay 7, to thel grounded battery 23. The relay 7 thereupon attracts its armature switch to establish a circuit traceablefrom the common grounded battery 23, the line switch interrupter 27. the armature switch ol this interrupter 27 and its contact. the armature switch of energized relay 7 and its contact. the upper armature. switch of the dciinergized relay 28 and its contact. theI top wiper of the master line switch 8 and the waiting contact engaged therehv. the motor magnet 2S), to ground. The motOl magnet is operated to turn the wipers` ot the switch 9 into engagement Nitllathe waiting contact-s belonging to the calling line il' such wipers are not already in such engagi ment.4 ll'hen the wipers ol the switch l? thus encounter the waiting contacts o a calling line a circuit for stopping the motoi magnet 29 is established. this circuit being traceabh` from the grounded battery '12%. the winding ot' relay 2H. the intermediate wiper of .the master line switch the waiting` cou tact engaged by thi, wiper. thiI bottom wiper ot thecinphnei switch il. the nailing contact engaged b i this wiper. the upper armature switch ot energized liney relay n belonging to the calling line and its cmg/:ccd contact. to ground. The rela). if@ energized to open a circuit lor the magnet ill? ai' the lippe: acnriaic \-\.`it'il: of said relay. Another circuit iesiabislicil which is trai-caldi l'r. the lor-'er cuando? armature switch ot relay :in and its nor, engaged contact. the intermediate. armatoril switch of deincrgizcd relayll-and iis contact the winding ot relay l.totlie groui'idcd battery Q3. 'l'he relay l?) cs aldishes a circuit traceable from its upper and grounded ai mature switch. the contact ol' this switct. the top wiper ot the upper call distribute;- switch 12. the waiting contact engaged by this wiper. the upper arniat-uiw switch oi' relay 32 and its normal contact. the winding of relay 33. to the grounded batter) 23. The energized relay Il establishesl a circuit trace able from its lower grounded armature switch. the contact engaged by thisl switch. the bottoln wiper ot the lower call distributer switch lliaud the waiting Contact en gagcd thereby. the relay l() ot" this switch 12. to the grounded battery 223. 'l`he encrgized relay fit establishes a circuit traceable from thc grounded battery 2o. the motor magnet Ill oi' the lower switch l2 (the up per ,switch l2 pertaining to the major group that includes thc minor group partially il!n--;'rnc=.l in Fig. Il. while the lower switch 1;' pertains tothe other major group). the :irnnitue Y vitch of this magnet :ind i conta the ottoni armature switch of lay and its contact. the bottom arma ture switch ot' relay 35 and tbe normal con` tact thereof pertaining to the Lower switch ing switch 11, cooperates with this` latter switch in causing the calling line to become connected with the wiper of some line extending switch 10, the line extending switch employed having its wipers associated with the said switch 11. The motor magnet 37 ot' such switch 10 is operated to move its wipers into connection 'with the contacts that are connected with the wipers of the switch 9 that is connected with the calling line unless the wipers of such switch happen already t0 the connected with the waiting contacts that are individual to such switch 9. The circuit of such motor magnet 37 is l traceable from ground through the winding of such motor magnet, the next to the lowermost waiting contact engaged by the' correspending wiper of the upper .switch 11, said wiper, the next to the uppermost wiper of the uppei switch 12 and 'the .waiting contact engaged thereby, the upper armature switch of relay 38 and its contact (belonging to the upper switch 12), the lower armature. switch of relay 13 and its contact (belonging to the upperswitch 12), the arma-- ture of the interrupter 39 and its contact (belonging to the upper' switch 12), the winding of said interruptor, to the grounded battery 23. The motor magnet 37 will operate to move the wipers of the employed switch l() untilthey engage the waiting contacts that are connected with the wipers of the employed switch 9 and inasmuch as the wipers of the switch 9 are now connected with the calling line, suchicalling line is exi tended into connection with the wipers of the employed switch 10 inasmuch as the motor 37 will cease operation when this connectionhas been established( The circuit by which the motor magnet 37 is caused to cease operation is traceable from the grounded battery 23, the winding of relay 38 pertainu ing to the upper switch 12, the intermediate wiper of this switch 12, the waiting contactfengaged by this wiper, the third from the bottom of the wipers pertaining to the upper switch 1l, the. waitingcontact en# gaged by this wiper, the bottom wiper of the employed switch 10, the waiting contact engaged by this wiper, the bottom wiper of the employed switch 9, the waiting contact engaged by this wiper, theupper armature switchv of the energized line relay 6 of the calling line, the contact'engaged by this armature switch, to ground. The circuit for the motor magnet is thus broken at the upper armature switch' of the energized re l lay 38 that belongs to the upper switch v12.

The lower armature switch of the energized, relay 3S pertaining 'to the upper switch 12` establishes a circuit traceable from ground, through the five hundred ohm resistance 40, the lower armature switch vof said relay 3S, the contact engaged b v this armature switch, the upper armature switch of the associate relay 30, the contact engaged by this armag waitin ture switch, the next to the bottom wiper of the upper swith. 12, the contact engaged by this wiper, the upper winding of relay 35 belonging to the upper switch l1, thebattery 23, to ground. The latter relay 35 being energized, establishes a circuit traceable fromthe grounded-battery 23, through the upper winding of this ,relay 35, (of preferably two hundred fifty ohms resistance), the top armature switch of this yrelay 35, the contact engaged thereby, the top armature switch ofthe associate relay 41,'the contact engaged by this latter armature switch, the next to the top wiper ofthe upper switch 11, the contact engaged byv this wiper, the top wiper of the employed switch 10, the

top. wiper of the employed switch 9, the waiting Contact engaged by thislatter wiper, both sides of the calling line and the telephone receiver, transmitter and switch hook at the calling station, the next to thetop wiper of the employed switch 9 by way of the waiting contact engaged thereby, the next to the top wiper of the employed switch 10 and the waiting contact vengaged thereby, the third from the4 top ywiper ofthe upper switch 11 and the waiting contact engaged thereby, the upper intermediate armature switch of the relay 41 pertaining tothe upper switchll, the contact engaged by this armature switch, the next to the top armature switch of the associate relay 35, the contact engaged by this switch, the lower winding of this relay 3,5, to ground. The five hundred ohm resistance 40 pertaining to the upper switch 12 being also in parallel with the lower Winding of relay 35,' 4shunts a suiiicient amount of current through4 this relay to maintain it energized.

The relay 35 under discussion establishes a circuit traceable from the grounded arma.- lture switch shown immediately above the core of this relay, the contact of this armature switch, the mi die wiper of the upper switch 11, the waiting contact engaged by energized to open circuit through theline 'relay G of the calling line. The 'circuit esl tablished through the lower armature switch of this relay 6 is opened to open the circuit of relay 7 whose .armature switch is released to open the circuit previously traced through the interrupter 27 and the motor magnet 29 pertaining to the employed switch Contact engaged by this wiper, the

9, whereby the wipers .of the employed 130 switch 9 are permitted to ,remain in connection with the calling line. The relay 42, being in the circuit through which the .cutoff-relay 25 of the calling line is ener- `gized, attracts its armature switch to estabA ish a circuit traceable from ground,through this armature switch, the Contact engaged by the armature switch, thelower wiper Aof the master line switch 8 and the waiting 'coni tact engaged thereby, `the winding of relay 26, the battery 23, to ground.l The bottom armature switch of relay 26 establishes an apparent circuit for the motor magnet 43 pertaining to' said switch 8, whereby the wipersiof this switch are moved from association with theemployed switch 9 into association with some idle switch 9, l.the moye- -ment of the wipers of the switch 8 continuing until the bottom wiper of this switch en` gages a waiting contact that is disconnected from groundlv at some denergized relay 42. The same interrupter 27 which was previously associated with the employed group of telephone lines.

switch 9 is now associated with the new switch 9 preparatory to takingpart in effect` ing the operation of this new switch when another call in -the Same minor group is initiated, By this arrangement I make the interrupter- 27 common to a plurality of line switches 9 that pertain to the same minor The next to the ottom armature switch of the energized relay 35 pertaining to the upper switch 11 establishes a circuit traceable from ground, through this armature switch, the contact egaged thereby, the bottom wiper of the upper switch 12 and the contact engaged thereby, the relay 30, the battery 23, to ground.A The bottom armature switch of relay 30 establishes an operating circuit for the motor magnet 31 pertaining to the upper switch I2 which switch contact of this motor muguet, the bottom armature switch of the associate re lay 30 and the contact engaged thereby, the

A bottom armature switch of the relay 35 pertaining to the upper switch 11, the normal Contact of this armature switch, the two left hand contacts of the button 3G pertaining to the upper switch 11, to ground. Said lnotor magnet 34 is operated to vbring the wipers of the upper switch 12 into connection with the i8 'made common to all of the motor niagiuirf` 3 7.perta1n1ng to a major group of telephowv is traceable from the` grounded Vbattery 23, the winding of said motor magnet, the armature switch and- 4G and its normal contact` to ground.

lines.

As will be understood from the descrip tion previously given, there is 'a switch 1,1 individual to each'major group of lines each operators position and if both of thcsf. switches 11 pertaining to a major groupic lines are busy the circuit of the driving magnet 34 will opened at the bottom 7.5 armature switches of the relays 35 pertaining to these two switches 11 so that the wipers of the upper switch 12 will remain ir engagement' with the waiting contacts pertaining to the switch 11 last selected, this i vei'igagemcnt continuing if the switch l1 hist selected is the first to be released. but boing broken if the converse is the c to a:-:.;ociatc wipers 12 with the other switch 1l that released. The Swich ll that has become associated with the calling line is employed to bring the calling line into connection with the operator having such switch ll and if the wipers ot' the holding relay selector switch 15 are not already connected with the so employed switch 1l they are brought into connection therewith duc to the estahlishlnent of a circuit at thc bottom armaturac switch of relay 35 of such switch ll` this circuit heilig traceable from tlul grounded hatw 93 tery 23. the winding of relay lt. the upper armature switch of the previously energized relay 33 (pertaining to the emphced switch 11) the contact ot' this armaturl` switch. to ground. The relay fl-l establislws :i circuit for the motor magnet l5 of the switch l5 which is traceable from the groundcd battery 23. the winding ot thc nmgnct l5. thc armature switch and contact ot' this magnet. the armature switch ot' relay -ll :md its coutact, thc lower arnmturc `switch oi' thc relay ll'hcn the wipers ol' the switch l5 have hccomc con nected with au employed switch ll. thc or eration of the motor nmgnet 45 ccascs owing 110 to the encrgization of relay 46 whose circuit that is thereupon cstublishcd is traccublc from the grounded battery 23. thc winding of relay 4G, thc bottom wiper ol' switch l5 and thc waiting contact engaged thcrcid. the alternate contact ot' the bottom arnmlure switch of relay 35 belonging to the employed switch 1l, said armature switch. the .left hand pair of contacts belonging to the hey 3G pertaining to the employed switch 1l`v to ground. The'energized relay 46 stops the lmagnct 45 by breaking the circuit for this magnet at the normal contact of the bottom armature switch of relay 46. The upper armature switch of relay 46 establishes a circuit trac-cable from ground through this armature switch. the contact engaged thereby, the lower intermediate wiper of the switch 15, the Contact engaged by this wiper, the armature switch immediately beneath the core of relay 35 pertaining to the employed switch 11, the contact of this armature switch, the winding f of relay 32, to grounded battery 23. .The relay 32 ot' the employed switch 11, being energized, opens a circuit for the relay 33 at the top armature switch of such relay 3Q, the upper armature switch of the relay 33, thus denergized, opening the oircuit'for the relay l-l belonging to the employed switch 15 to prevent the magnet 45 from operating when the relay 16 is denergized. The lower armature switch of said denergized relay 33 removes ground from the bottom waiting contact of the lower switch 1:2 to allow the wipers of this lower switch 12 to stop in connection with the lower switch 11 pertaining to the operator having the aforesaid switch 15 so that auother call can lay in upon this opcrator`sI position while the operator is taking care of the 'call about which she is receiving infor mation through the upper switch 11.

If the exchange should be of larger capacity than that chosen as au example. each operator would have more than two holding switches 11 and in such event each relay v 33 would have one armature added for each additional switch 11 supplied to each operator, the circuit environment of each added armature being similar to that illustrated at the bottom armature switch of each illustrated relay 33. It' it should be desired to throw any switch 11 out of service the button 36 individual thereto may be depressed by a chief operator to a locking position, thereby removing the ground at this button whose aid is required for the employment of the switch having the button. the ground being transferred to the right hand contact of the switch 36 which is connected with the bottom waiting contact of the associate switch 12 whereby said associate switch 12 cannot have its wipers stopped upon waiting contacts that belong to the switch 11 whose button 36 is thus depressed. As a consequence of the association of the holding relay selector switch 15 with a call holding switch 11 circuit is established for ener gizing relay 4T individual to the selected operators position, this circuit being traceable from the grounded battery 23, the winding of said relay 47, the upper armature switch of relay 4.3 individual to the selected operator, the contact ot this armature switch, the armature switch of relay 49 individual to the selected operator and the contact of this armature. switch` the lower armature switch of energized relay 32 of thc employed switch 11, the contact ot' this ar mature switch, to ground. The lower arma ture switch of relay 47 establishes a circuit traceable from the grounded battery 23, the winding of relay 50, the lower armature switch of relay 51 and its contact, the lower armature switch of energized relay 47 and -Y() is -now energized and its contact, the alternate contact of the loiv'cr-ai'niatiire switch of energized relay 46, this armature switch, to ground. Relay establishes, at its upper armature switch, the illustrated local circuit for the signal Q1 individual to the selected operator to attract the attention of this operator if she is not at her position. The lower armature switch of relay 50 is separated from its contact to open the shunt which is preferably maintained across the terminals of the operators head telephone 5 during the operation of the switches and until the telephonie circuit between the lected operator and calling subscriber is completely prepared. When this condition has been reached the operators head telephone 52 is brought into telephonie circuit with the two top wipers of the employed switches l5, 10 and 9 and the second and third wipers from the top of the employed switch 11` whereby the calling subscriber may talk ,to the selected operator.

The battery current for the calling subu scriber is furnished from the battery 23 by way ot the windings of the relay 35 of the employed switch 11. The operators trans. initter 53 is provided with a connecting plug 54 receivable within a jack 55, the two terminals of the jack being connected through the two windings of a' relay 56, the terminals of one of which being directly grounded while the terminal of the other is grounded through the common battery 23. When the plug and jack are connected a local battery circuit is established through the' transmitter, this circuit including a primary coil that is in inductive relation with the sec ondary 58 which is included in the circuit of the head telephone 52. The condenser 59 is in bridge of the transmitter circuit to prevent the telephonie currents from being shunted from the line by the relay 56. Condenser 60 is included in circuit with the operators head telephone to prevent the passage of battery current therethrough. lVhen the plug 54 is inserted within the jack 55 the relay 56 is energized, the upper arma ture switch of the relay 56 establishing a. circuit for the designating lamp 20, which circuit is traceable :from the grounded battery Q3, the lamp 20, the top wiper of the master cord switch 17 and the contact engaged thereby. the relay 61 dcsirably of one, hundred ohms resistance, the upper armature switch of the energized relay 56 and its contact. to ground. The lamp 20 glows and the relay 61 is energized to move its armature switch from its normal contact into engageiuent with its alternate contact if the lament of the lamp 2O is notl broken. Itv

the lamp 20 does not glow because of its broken filament or other open circuit ,condition. the relay 61 will not energize and a circuit will be established for the motor magnet 62 which is traceable from the grounded common battery 23, the armature oi' the motor magnet 62, and its contact, the

winding of magnet 62, the armature switch of relay 61 and the normal contact of this armature switch, the lower armature switch' in assisi-,lation with the latter lamp to cause it to glow.

The operator, having ascertained the number of the wanted line, will insert the plug' 16, which is individual to the glowing lamp 20, in the jack 19 belonging or pertaining to such wanted line. The operator will depress the button 22 to establish a circuit traceable from the ground applied at the switch upon vthe uppermost armature switch of energized relay 47, circuit continuing through the, alternate Contact of this armature switch, the winding of relay 51, to the grounded battery The operator then releases the button 22 to remove the ground there applied, a locking circuit having been established by the energized relay 5l traceable from the battery 23 through the winding oi' relay 51, the upper armature itch of relay 51 and its contact, the intermediate armature switch of energized relay 47 and its contact, the winding ot' relay 63, to ground. The relay 63 is energized, a circuit being established traceable from ground', 4 y bottom armature switch of relay 625, 'the contact ot this armature switch, the bottoni armature switch of relay 64, the contact ot this latter armature switch, next to the bottom wiper of the switch 17, the waiting contact engaged by this wiper, the Anext to the bottom armature switch of relay 65. the contact of this armature switch, the motor magnet 66, the armature of this motor magnet, the contact of this armature, to the grounded battery 23. The motor magnet 66 pertains to the switch 16 whose wipers are telephonically connected with the employed plug 16, the motor magnet 66 continuing in operation until the wipers of the switch 16 engagewaiting contacts that are connected with the wipers belonging to the employed switch l0, it being understood that the motor magnet 66 does not operate if it should happen that the wipers of the switch 16 already are in engagement with waiting contacts that are connected with the wipers ot' the en'iployed switch l0. When the wipers ot the switch 16 are thus engaged with waiting contacts that are connecte with the wipers oi' the em loyed switch 10 circuit for the motorrnagnet 66 is opene switch switch of the busy test at the lower armature switch of relay 64 owing to the energization of this relay which occurs due to a circuit traceable from the grounded battery 23, the winding of relay 64, the third from the bottom Wiper of the switch 17, theA waiting contact engaged by this wiper, the bottom wiper of the switch 16, the waiting contact engaged by this wiper, the top wiper of the employed switch 11, the waiting contact engaged by this wiper, the upper armature switch of the en ergized relay 32 pertaining to the employed 11 and the alternate contact of this armature switch, the bottom armature switch of energized relay pertaining to the einployed switch 11 and the alternate contact ot this armature switch, to the grounded contact of the switch 36. The upper armature switch of energized relay a circuit traceable from the grounded battery 23 through the intermediate armature switch of relay 63, the contact of this armature switch, the five hundred ohm resistance 67, the upper armature switch of energized relay 64 and the contact of this armature switch, the third from the top wiper of switch 17 and the waiting contact engaged by this wiper, the lower winding of relay 65, to ground. Relay 65 is'now energized to attract all of its armature switches, the two top armature switches connecting the tWO top wipers of the switch 16 with the talking contacts of the employed plug 18, circuit through the relays 25 and 42 being now maintained at the energ1zed relay 65. middle wiper of the switch 16 is grounded at the middle armature switch of the energized relay 65' for the purpose of maintaining the relays ft2 and 25 associated with the calling line, energized. As another consequence of the energization of the relay 65, and under the assumption that the desired line is idle, a circuit is established for the ringing control relay 68 which 4is traceable from the grounde battery 23, the third from the top of t e armature switches of relay 65 and the contact engaged by this armature switch, the bottom armature relay 69 (which is not energized if the called line is idle) and its normal contact, the winding of relay 68, the second from the top of the wipers of switch 17 and the contact engaged thereby, the top armature switch of engaged contact, to ground. The top armature switch of energized relay 68 establishes a locking circuit for this relay which is traceable from the grounded battery 23, the third from the top of the armature switches of energized relay 65 and the contact engagcd by this armature switch, the bottom armature switch of the busy test relay 69 and its normal contact, the winding of relay 68, the top armature switch of this relay, the Contact engaged by this armature switch,

The

relay 63 and itsV 64 establishes loro switch is moved into association with a new Y and idle switch 10, a result which is due to the establishment of a circuit traceable from the grounded battery 23, the' relay 41 of this .switch 11, the bottom wiper of this switch and the waiting` Contact engaged thereby, the neXt to the bottom wiper of the employed switch 16 and the waitingr contact engaged thereby, the armature switch immediately above the core of the relay 65, the contact engaged thereby, to ground.

The energized relay 41 establishes a ci.ru cuit traceable from the grounded arma ture switch immediately below the core of this relay, the contact engaged by this armature switch, the armature switch and contact of motor magnet 71 of the switch 11 under discussion, the winding of this motor magnet, to the grounded battery Q3. This motor magnet 71 operates until the bottomwiper of said switch 11r encounters a waiting contact which is ungrounded at the next to the bottom wiper of someother and idle switch 16, this latter wiper being ungrounded when the associate relay 65 is denergized. rl`he relay ilf/'ofsaid switch 1l, by attracting its two top armature' switches, breaks the bridge connection by way of the relay 35, which was included across the connection established between the calling subscriber and the selected operator whereby such operator is excluded from connection with the calling subscriber. The feeding of battery to the callingr line.' which occurred by Way of the relay 35 when the operator was connected with the calling line, is eliected, after the exclusion of the relay from circuit, by way of the battery .feed relay 65. Re stored armature switches of the denergized relay 35 open all the circuits that were maintained thereby to restore all apparatus in such circuits to normal. The operators telephone equipment is now `ready for connection with some new calling subscriber. The relay 4S pertaining tothe switch i7 that was associated with thenow energized.

relay 65 is energized by a circuit traceable from the grounded battery 233, the winding of the relay 48, the bottom wiper of the switch 17 and the waiting contact engaged thereby, the bottom armature switch of the relay 65, the contact engaged by this armature switch, to ground. A circuit for the motor magnet 62 is established which is traceable from the grounded battery the armature switch and contact of this motor magnet, the winding of the magnet, the bottom armature switch and contact of relay 48, the armature switch and alternate contact of relay 61. the bottom armature switch and contact. of relay 56, to ground. The inolay 65 associated with some idle plug 18.

Vtor magnet 62 continues in operation until its bottom wiper engages a waiting contact 'that islfung'rounded at the bottoni armature switch and contact of some deuergized re- The lamp #20 individual to such new plug 18 glows to predetermine this new plug 18 for use. The previously energized ringing control relay 68 causes the establishment of a circuit traceable from the grounded battery Q3, the winding of the sluggishly releasing relay 72, the intermediate armature switch and Contact of said relay 68, to ground. The energized relay 72 establishes a circuit for the cutoii relay 25 of the called line, assuming that such line is idle, which traceable from the grounded two hundred ,titty ohm resistance 7?, the lower intermediate armature switch of relay 72 and its altery nate Contact, the third or heel contact of the plug 18 inserted into the jack 19 of the wanted line, the thimble of such jack., the winding of the cutoff relay of the called line, to the grounded battery 23. The cutoil' relay 25 of'such called line. attract-s its armature switches to prevent the line relay 6 of the called line from responding when the called subscriber responds. Another circuit established by the relay 68 is traceable from the grounded battery :23, the wind 95 ing' of the intermittently operated ringing relay 74, the bottom armature 'switch and contact of the relay 68, to the grounded interrupter 75 that intermittently establishes circuit for the relay 7i. The two armature 100 switches of the ringing relay 74, which in their normal condition connect the employed plug 1.8 with the top wipers of the employed switch 16, are now attracted to engage their alternate contacts which are connected with the source of ringing current 76 that is thus included in bridge of the called line to operate the bell 4 that is in bridge of the line at the called station owing to the engagement of the switch hook thereat with its normal contact. After the called subscriber has responded and during the time that the circuit for the relay 74 is open at the interrnpter 75. a circuit is established thrnugli the relay 70 owing to the then denergiacd 115 condition of the relay 74. Talking battery is furnished to the called subscriber by way of said relay 70 whose energizing circuit is, traceable from the grounded battery 23, the upper winding of relay 70, thetop armature switch and Contact of relay 72, the top armature switch of relay 74 and its normal con` tact. the tip of the employed plug 18, the

tip spring of the jack 19 engaged by the tip ol' the plug 18, both sides of the called line 125 and the elevated switch hook, receiver and transmitter at the called station, the sleeve spring of the employed jack 19, the sleeve contact of the plug engaging this spring, the lower armature switch of the relay 74, the

normal rontsuft nl' thia witrh. the upper ntern'iediute :unuiture switeh ot relnv iz! :1nd the Colituf't el tired 'flierehj the iower ty to rif vom fn the "will 'the upmnlor will fate down the prrn l in-V fiixlfluzil to the l il :and r t1ne it nfo engagement with it. plug` Heut nniteh "[4 therein' etl'nrniis," ille sifnnl ennvej'ed h v he ll' the enllrd line in lnisv the relu); t# will not he ent-:glazed wl en the oprrntfn' inserti` the plug 'lin into the piel( of the hnrv wanted linel whereupon the him; tes-zt reim' tlf! will he energized hv :i eimnit trnr :dile from the 2@rounded luttent' i.l, the lower winding! ol' the lninv liest ret-rv Sin the lower intermediate zzriniiturr, sw'iteh of rehiv lL und its norinzd tart. the heel ol' the ping: lh. the thinilile t, lli-rjuilV en ig'inla the sznnm the multiple, ot' this jul-:lf thiinlde :it the operators pe irtien where eonneer e iih lie hiwvY wanted liiulmsslieen@Finish-1MLthe heul oi the ping: nl .u fui-"h other r-perrnor4 poition. the lnwer interine'lnite 1. rnritnre wiieh of energized rehtr i'z 1n' urli nther uperriiofl pom tion. the :alteran-:te rontinet ol3 thinarmatore uwiteh, to the gfreinded reaizltiu'n-c Til were ported with ihn` :'iilernute con t Hele." ut) pirtnining to the link hij which emineeioi'i if; Sought with the preriounlv husv wanted thi@4 relug rstnlflh-fhingf trueffzlhle troni ground. l thierl rrhzj". the hottoiu :i rilcniti for :zei imi" n f! the third trim:

to the grounded hutterlr 235. The top :trumtnrLI switehe ot' thi 4 rehrv tit) now inelnde the hns'v tone devire ."Sl in hridpie oll the line evtendintr to the milling' yntntion to indir; te if the willing' sulneriher thi-it the wanted line hns):

Vw'hile lnive herein ahown :ind pzirtien-` inrltY deferihed the preferred enilnnlinient' ott nl v in\ention Vl do not wish to he liinited to the preeiwxv detnil of eonstrurtimi :unl rircuit nrrninfennnt shown :in4 elninjge` nnrv reudil)v he nnnle without depuiting;- l'roln the spirit of in v invention` hut Iluvingf thus deserihed niv invention l elxliin ne new :ind deflire to neenre hi' Letti-wy lzitent the following:VVV

l. telephone exelnunfe System having,r telephone line` extendin} r lroni substation# to :in exrhzmg'e :ind whieh lines :ire sul4 divided into iunior lgroups with the linen of the nmior y'r'oupn divided into minor groups: line ,ww itehes, lor the telephone linenl in eneh irinm `sgroup for tziliing pzirt in the extension of railing taleplninn linen: :i munter switeh inlii idun to meh miner Igroup ot telephone lineI for renderlngj operzltne Sonie liner viti-,h pertnininu' tothe minor group havin.;r

nimter iteh: exehnnge operzitors` equipment' :it :i plnrrilitv ol opernt'ors` posi- :i culling` line operated dintrihnter finita-l: for ezu'h nizrior `group of telephone lines :unl eonnnon to the lines of sneh nniior Ironp for :issoeintinfg the equipment of :inv of the opernt'cns with the milling;r line einplining' it: :ind n plnrnlit)y ot' holding wvit'ehesI for eueh nnrior group ol telephone lin intt'irposed hetween the culling line operated distrihutrr Hwilehes and the operators` equipment tor holding` enlling lineny preparatori' to the eonneetion olA the equipment ol' eleeted operutors therewith.

:3. A telephone exelninge system having telephone lines extending troni SuhStutions to :in exelninge :ind whieh lines ure Subdivided into nmjor gironi with the lines of the niuior groin divided into minor group; line switehesv t'or the telephone linenl in eneh niinor group .-ind le in nuinher thun sneh trlephoi'ie line l'or tuliin;V purlr in the exteniion otl milling telephone lines: :t master switeh indi\id|r.1l toerirh 1ninor; {i'o\ipoltelephone linen l'or rendering.r operntive some line switeh pertuiningr to the minor group having; sueh muster lwilt-h: exchunge operzitorri' equipment :it :i plurality of operA :trom positions: :i milling line operated distrihuter switeh for eneh major group of telephone lines und Common to the lines of sueh nnrior group for nssoeiut'ing the equipment of any of the operador with the eiillinf,r line einploring it: :nid :i plurality of holding Swtel :n for r nl major `group of telephone linee; nner ini-tw en the milling line opa' iivitel'ws and the opt "1"' holding calling lines infn.

lll

prsqairatory to the connection of the equipment ot selected operators therewith.

2, A telephone exchange system having teit-phone lines extending 'from substations to i exchange and `which lines are subdi i i into major groups with the lines of the or groups divided into minor groups;

iin-f: switches for the telephone lines in each minor group i'or taking part in the extension oi calling telephone lines; a master switch individual to each minor group of telephone lines for rendering operative some line switch pertaining to thc minor group having such master switch; exchange operators equipment at a plurality of operators positions; a calling line operated uitf'iluiter switch for each major group oi' teiephone lines and common to the lines of such major group for associating the equipment of any of the operators with the railing' line employing it; means whereby the caliing line operated distrihnter switch i'rertaining to each major group of' lines is limited to the establishment' of connection between one operators equipment and one calling iine; and a plurality of holding switches for each major group of telephone.

lines. interposed between th'ey calling line operated distributor switches and the operators? equipment tor holding calling lines preyfuiratory to the connection of the equipment. of selected operators therewith.

l. A telephone exchange system haring telephone lines extending from snbstations to an exchange and which lines are divided into major groups with the lines of the maior groups divided into minor groups; line switches for the telephone lines in each minor group and iess in number than such tc cplmne lines for taking part in the extens.on of calling telephone lines; a master s\\'itfh individuai to each minor group of `telephone iines 'for rendering operative some line switch pertaining to the minor group haring such master switch: exchange operators equipment at a plurality of operators" positions; a calling" line operated distributer switch for each major groupof telephone lines and common to the lines oi smh major group for assiciating the equipr ment oi' any of the operators with the calling line employing it; means whereby the calling line operated distributer switch pertaining to each major group of lines is limited to the estabhshment of connection between one operators equipment and one calling line; and a pim-ality of holding switches for each major group of telephone lines interposed between the caliing line operated distrihuter switches and the operators equipment for holding fai'iing lines preparatory to the connection of' the M fupment of selected operators there with.

Si, )i trlephone exchange system having tetphone lines extending from substations to anv exchange and which lines are subdivided into major groups with the' lines of the major' groups divided into minor roups; line switchesfor the telephone lilies 1n each minor group and less in number than such telephone lines for taking part in the extension of calling telephone lines; exchange operators equipment at a' plurality oi operators positions; a calling line operated dlstributer switch for each major 'group of telephone line-s and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it; and a plurality of holding switches for each major group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith.

6. A telephone exchange system having telephone lines extending from substatious to anexchange and which lines are dividedh into major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each minor group and less in number than such telephone lines for taking part in the extension of calling telephone lines; exchange operators equipment at a plurality of operators positions; a calling line operated distributor switch for each major group oi telephone lincs and common to the lines of such major group for associating the equipment of any ot' the operators with the calling line employing it; means whereby the calling line operated distributer switch pertaining to each major group of lines is limited to the establishment of connection between one operators equipment and one calling line; and a plurality of holding switches 'lor each major group of telephone lines interposed between the calling line operated distributor switches and the operators equipment for holding calling lines preparatorv to the connection of the equipment of selected operators therewith.

7. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdinided'into grups; line switches for the telephone lines in each group and less t .an the number of such lines; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each group of telephone lines and common to the lines of such group for associating the equipment of any of the operators with the calling line employing it; and a plurality of holding switches for cach group of telephone lines interposed between the 'ailing line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection some line switch pertaining.r to the minor group having such. master switch; exchange operators" equipment at a plurality of 4operators positions; a calling line operated distributer switch for each major group of telew phone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it means whereby the calling line operated distrihuter switch pertaining to each major `egroup of lines is limited to the establishment of connection between one operators equipment and one calling line; a plurality of holdin g switches for each ma jor group of telephone lines interposed bctween the calling line operated distriliuter switches and the operators` equipment for holding calling lines preparatory to the conm nection of the equipment of selected oper ators therewith; and holding selector switches forV transferring operators tele phone equipment troni holding switches to holding switches.

lil. A telephone exchange system having telephone lines extending from substations to an exchange and winch lines are divided into major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each mi nor group and less in number than such telephone lines i' or taking part in the extension of calling telephone lines; a master switch individual to each minor group of telephone lines for rendering operative some line switch pertaining,r to the minor group having such master switch; exchange operators equipment. at a plurality of operators positions; a calling line operated distributer switch for each major group of telephone lines and common to the lines of suoli major group for associating,y the equipment of any of the operators with the calling line employing it: means whereby the calling line operated distributor switch pertaining to each major group of lines is limited to the establishment' of connection between Vone operator`s` equipment and one calling line; a plurality of holding switches for each ma- Lior group of telephone lines interposed bctween the calling' line.operated distributer switches and the operators equipment for holding!` calling lines preparatory to the connoction oi' the equipment of select-ed opera' tors therewith; and holding selector switches for transferring operators telephone equipment from holding switches to holding switches,

15. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into major groups with the lines of the major groups divided into minor groups; lines switches for the telephone lines in each minor group and lessI in num berthan such telephone lines for taking part in the extension of calling telephone lines; 'exchange operators equipment at a plurality of operators positions; a calling line operated distributor switch for each major group of telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing 1t; a plurality of holding switches for each ma jorgroup o'f telephone line interposed be tween the calling lines operated distributor switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith g and holding selector switches or transferring operators telephone equipment from holding switches to holding switches.

16. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are dividedv into major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each minor group and less in number than such telephone lines for taking part in the extension of calling telephone lines; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each major group of telephone lines and common to the lines of such major group for associatingthe equipment ot any of the operators with the cal ing line employing it; means whereby the callingr line operated distributer switch pertaining to each major group Yof lines is limited to the establishment of' connection between one opcrators equipment and one 'alling line; a 1plurality of holding switches for each major group of telephone lines interposed between the calling line operated 'listributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operator@ therewith; and holding.' selector switches for transferring operators7 tele'lihone equipment from holding switches to holding switches.

17. A telephone exchange system having telephone lines extending from. substations to an exchange and which lines are subdivided into groups: line suf'itches for the telephone lines in each group and less than the number or .nich lines; exchange operators equipment at a plurality of operators posit-ions; :i callingV line operated distributor switch for cach group ot telephone lines and common to the lines of such group for associating the equipment oi' any ot the operators with the calling line employingY it: a plurality of holding switches for each, group ot' telephone linesl interposed between the calling line operated distributor switches and the operators equipment for holding calling lines preparatory to the connection of tlul Oquipincnt o l' solortwl oparators thoro- -u'ith'z Iand holding whit-tor :uvitchcs for tranlorring oporators toluphonv vquipnioni, from holdin;Y riti-hrs to holding: ,Utili-hr. 1N. Lolophono o.\ han'o Systran haring tolvplioiu' |in0 A oxtvnding' troni sulistations to an otrhang'o and whirh linol aro uliv diridvd into groups: twhangv opuratoml mluipnuut at a pluralit ot' opvratoiz# positions; a vulling' lino oporal-d distributor \\'it -h for laih `'roup ot' lin 4 and ronunon to the linos ol' uth group l'or assoriatinij tho 1 |uipnwnt of any of tho oporatoh with thil milling' lintI viuploiin;I it: a plurality olA holding \\'itrlu^,- for mail `group of tulrphono lino intrrpo 1od liriwifvn thtl calling linr oporalod distributor mvitrhos and tho opvralor@ equipinont for holdin;Y ra linz: liniwl proparator)Y to thv ronnoction ol' thi1 oduipniont of ,wlortod opvrators tlirrcwilh: and holding wlorlor sivitrluv for transfer-- ring' oprrators.` trlopliono iquipnif-nt 'l'rouz holdinguitrhvu to holdingA #uilrhvx ISL A tolvplionr oxvlmngr .ayalrni having; trliephoiw lino` oxtvndiug troni auhatatioiwV to an vxrhango and u'hirii limos ari) .sull-di vided into groups: lim` .-:\\itrho,-; for ilutulo phon@ lints in farli lgroup and Irvs than dir nuninvr ol' surh lint-h: vxvlmugjp oprratoi. Acquipnunt at a plurali)v of oporators' i .L lions; a Calling" lino oporabd distributor switrh for x:uh Agroup olA tolvphonv lines and ooniinon to tht linuxl ot' surli group tor assi ('iatingl th(x oquipnunt of any of the opurators with tho willing' limA miniloying il: moans llorohy thel willing linil oporatid dis trihuter switrh pcrtainingr to Carli `Lroui'i ol' linvs is lilnited to thc ostalilislunrnt of Con'- nvrlion lwtwoon om` operatoifs equipinont and ono callingr lino; a pluralit)v of holding switches for earh iroup ot' trlephono linra imm-posed limtwcen tho calling lintx oporatod (.listriliutor switchow` and thoy opcrators` oquipnufnt tor holding railing linos prcpar atoryr to thix ronnortion ot' tluA equipment ol solortod operatora thcrouitli: and holding; selector switches 'l'or transtoringv operaio` tolophono.oquipniont from holding su'itrhw to holding switches.

20. A telephone xi-hangr vait-in having tehphonix lino exti-lulin;r Vtroni snhstations, to an vxrliangro and whirli linos are sulidi vided into groups: cxvhangr operators` oquipinent at a pluralit;Y ot' operators posi tions: a vulling lino opel-alud distributor switch for Qarh group oll lines and tol'nnion to the linrs of surh group for associating thv oquipnunl of an)y o'l' thv oprrator@` with tho milling' lino oniploj'ingv it: nuirins whor:I l thtl walling lino oporatwl distriuitrr switrh pi-rlainingar to rarh glroup olA 'l s liniilod lo the ostalilislunont ol' ronnootion lwtworn ono opor-intona4 Uquipnwnl and out 'alling lino; a plurality o holdingv switches tur nach `group ol' wlrphoi'u lint-ry ii'iiiri atwoen tlu` walling lino opyratwl distriiauer f-,\\'itrlu\`Y and tlua opvralor;\` orfuipnwut for holding milling' linr.`v pwparao'y lo tht` von no4-tionolllwvnuipnwntotsifiorlrdop-l::1or: thorpa ith: and holdin; olv-tor :fa iuhw for traint'ffrringf op atari iifipliona ripiipuwuiV 'lroni holding mvitflu` lo holding; wziiiflu's. 2l. A\ tolophonr xrleangjv uztoxn haring" trliplionv linrs ouoiuling troni snhitation 1o anwxrliangg'o and uliirh lint artA uuhelr ridofl into nia1 "r group with ihr l ot' tha; maior groups dir 'wd into nunorgroup lim .'riti hrhior thv vlag" Q in @urli minor froup for Fai'iing par Y- tutti* nlt ialingj viopliono lum-i a immun iii-.lli iilusl tu varia ruinm 19' loll-pluim Einw for rison'u! l ,qwir pai unina` to ilu' ininrr group 4m-li mar "1' .-wiirix; o'ieratfue.' oipiipin nt u! -n pluralir iipvratoi,

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to mim r frm vastral di 1 lll V.ailing minding miriam for l there being means whereby the holding switches may select and enable the operation of calling line extending switches.

23. A telephone exchange system having telephone lines extending from substations to an exchange andfwhich lines are'subdivided into major groups with the lines of the majorgroups divided into minor groups; line switches for the telephone lines in each minor group for taking part in the extension of calling telephone lines; a master switch individual to each minor group of telephone lines for rendering operative some line switch pertaining to the minor group having such master switch; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each major group of telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the callin line employing it; means whereby the calling line operated distributer switch pertaining to each major group of lines is limited to the establishment of connection between one operators equipment and one calling line; a plurality of holding switches for each major group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; and calling line extending switches for elxtending calling lines7 there being means whereby the holding switches may select and enable the operation 'of calling line extending switches.

24. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are divided into major groups with the lilies ofI the major groups divided into minor groups; line switches for the telephone lines in each minor group and less in number than such telcphone lines for taking part in the exten- -sion of calling telephone lines; a master switch individual to each minor group ot telephone lines for rendering operative some line switch pertaining to the minor group having such master switch; exchange operators equipment at a plurality of oper-k ators positions; a calling line operated distribnter switch for each major group of telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it; means whereby the calling line opera-ted distributer switch pertaining to each major group of lines is lim- 4.ited to the establishment of connection be- 'tween one operators equipment and one cally ing line; a plurality of holdingswitches for each major group of telephone lines interposed between thecalling line operated distributer switches and the operators equipment for holding calling lifnes preparatory to the connection of the equipment olf selected operators therewith; and calling line extending switches ;tfor extending calling lines, there being 'means whereby the holding switches may select'and enable the operation of calling line extending switches.

25. A telephone exchange system having telephone lines extending from substatioiis to an 'exchange and which lines subdivided into majorgroups with the lines of the 'major groups divided into minor groups; line switches for thelelephonc lines in each minor group and less number than. such telephone lines fori takiig part in the extension of calling telephone lines; exchange operators equipment at a plurality of operatorsy positions; a calling line operated distributer switch for each major group of telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it; a plurality of helding switches for each major group of telephone-lines interposed between the calling linel operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment oi selected operators therewith; and calling line extending switches for extending calling lines, there heilig means whereby the holding` switches may select and enable the operation of calling line extending switches. l

26. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are divided into: major groups with the lines of the niajor groups divided into minor groups; line switches for the telephone lines in each minor group and less in number than such telephone lines for taking part in thfe extension of calling telephone lines; ex, aange operators equipment at a plurality of o'perators positions; a calling line operated lli? distributer switch for each major group o telephone lines and common io the lines of such major group for associating the equipment of any of the operators with the calling line employing it; means whereby the calling line operated distributer switch pertaining to each nza jor group of lines is limited to the establishment -of connection between onelo'perators etuipment and one calling line; a plurality` o .5 telephone lines extending from substations to an exchange and which lines are subdivided into groups; line switches for the telephone lines in each group and less than vthe number of such lines; exchange operators equipment at a plurality ot' operators positions; a calling line operated distributer switch for each group of telephone lines and common to the lines of 'such group for associating the equipment of any of the operators with the calling line employing it; a

plurality of holding switches for each group of telephone linesl .interposed between thecalling line operated distributor switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith: and calling line extending switches for extending calling lines, there being means whereby the holding switclies'iiiay select and enable the operation ot calling line extending switches.

28. A telephone exchange system having telephone linesl extending from substations to an exchange and which lines are subdivided into groups; exchange operators equipmentat a plurality of operators7 positions: a culling line operated distributer switch for each group of lines and common to the lines of such group for associating theequipmentpt' any ot the operators with the calling line employing it; a` plurality of holding switches for each group ot telephone lines interposed between the calling line operated distributer switches and the 40 operators equipment torA holding calling lines preparatory to the connection of the equipment of selected operators therewith; and calling line'extending switches for extending calling lilies, there being means whereby the holding switches may select and enable the operation ot calling line extendirqfI switches.

29. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdi vided into groups: line switches for the telephone lines in each group and less than the number of such lines; exchange operators i equipment at a pluralityof operators posiy tions: a calling lineoperated distributer switch for each group of telephone lines and common to the lines ot' such group for associating the equipment of any of the operators with the calling line en'iploying it; meansA whereby the calling line operated distrihuter switch l'iertainiug to each .group of lines` is limited to the establishment of con-- nection between one opcrators equipment and one calling line; a plurality of holdJng switches for each group of telephone lines interposed between the calling line operated distributer switches and the operators vequipment for holding calling lines prepara-tory to tli'e'connection of the equipment of selected operators therewith; and calling line-extending switches for extending-calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches.

line: a plurality ot holding switches for. `cach group ot telephone lines interposed between the calling line. operated distributor switches and the operators" equipment for holding calling lines preparatory to the connection of the equipment ol selected operators therewith; and calling liiievextending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches.

3l. A telephone exchange system having telephone lilies extending from suhstations to an exchange and which lines are subdiw'ided into inajoi' groups with the lines of the major groups divided into Vminor groups; line switches for the telephone lines in each minor `group for taking part in the extension of calling telephone lines; a mas tei' switch individual to each minor group of telephone lines for rendering operative some line switch pertaining to the minor group haring such master switch; exchange operators equipment at a plurality of opcratorspositions; a calling line operated distributor switch t'or each major group of telephone line-s and common t0 the lines of such major group for associating the equipment ot any ot' the operators with the calling line employing it: a plurality of holding 'switches for each major group of telephone lines interposed between the calling line'op era'ted distributer switches and the operatorsn equipment for holding calling lines `preparatory to the connection of the equip ment ol selected operators therewith holding selector switches for transterring opera-tors7 l telephone equipment from holding switches to holding switches; and line extending switches for extending calling lines, there 

